STROKE PATIENTS WITH AND WITHOUT HYPERTENSION: DISCUSSION
Our study showed baseline differences among the non-hypertensive and hypertensive AAASPS enrollees. Specifically, the non-hypertensive African American enrollees were more likely to be current cigarette smokers and have higher education, and less likely to have old CT/MRI-based infarcts. On the other hand, hypertensive AAASPS enrollees, in addition to having htn, were more likely to have other metabolic risk factors such as diabetes and trends for history of hypercholesterolemia, and other factors such as angina pectoris and history of prior stroke. The constellation of metabolic abnormalities that include dyslipidemia, glucose intolerance and htn may cluster in individuals and families and is known as Syndrome X. Syndrome X predicts cardiovascular disease risk and may also include such factors as hyperuricemia, impaired fibrinolysis and small dense LDL particles. Prevention and treatment of some of the risk factors that compromise Syndrome X reduce the risk of a first stroke.
Interestingly, our non-hypertensive study subjects were more likely to be current cigarette smokers. Cigarette smokers may be less likely to be hypertensive as they stop smoking prior to blood pressure determinations as recommended in national guidelines for measuring blood pressure; are leaner; or they may be educated less substantially by their physicians to stop smoking if they do not have other stroke risk factors.
Based on risk profile we suspect that our AAASPS patients with htn will be at higher risk of stroke recurrence than non-hypertensive AAASPS patients, because our hypertensive patients have a risk profile conducive to late stroke recurrence. Based on data from the Northern Manhattan Stroke Study (NOMASS), a racially-mixed study population, Sacco and colleagues have concluded that such factors as htn, heart disease, hyperglycemia, and history of TIA or prior stroke are probable predictors of late stroke recurrence. Other probable predictors of late stroke recurrence may include age, congestive heart failure and atrial fibrillation.
Stroke subtype is a predictor of both late and early stroke recurrence. Those with atherosclerotic stroke have a relatively high risk of late recurrence and those with lacunar stroke a low risk. Early stroke recurrence is highest for large artery cerebrovascular disease followed by car-dioembolic stroke, and lowest for lacunar cases. Other predictors of early stroke recurrence include htn and elevated blood glucose. Thus, we would predict that our hypertensive patients in AAASPS are at higher risk of early and late stroke recurrence when compared to our non-hypertensive patients. Finally, in the Stroke Data Bank a multivariate model suggested that patients at lowest risk of stroke recurrence within two years included those with low diastolic blood pressure, no history of prior stroke, no history of diabetes, and an infarct subtype of unknown cause, a low risk profile consistent among many of those in our non-hypertensive AAASPS group.
AAs may be more seriously ill after stroke, have longer length of stay in the hospital and more severe altered level of consciousness, and more physical impairment but a similar degree of functional impairment after stroke as other stroke survivors. When the AAASPS concludes we will be able to study physical and functional impairment at entry into the study, at follow-up, and when there is stroke recurrence. Stroke severity may be a predictor of death or dependence at six months. Other stroke outcome predictors may be age, gender and education level. Stroke severity may also be a predictor of patient well-being. online canadian pharmacy
Our study has several potential limitations. First, although AAASPS represents small, medium and large-sized hospital-based patients that serve the African American community, it is not a population-based study and may not be representative of the African American community at large. Second, since the AAASPS is a clinical trial with specific inclusion and exclusion criteria, it is possible that selection bias could determine how patients with specific risk profiles entered into the study, thus biasing the results. Third, there could be unmeasured potential confounding factors such as genetic factors, inflammatory or infectious markers, or metabolic factors such as homocysteine that could explain our findings. Whereas this could explain part of the variation, we suspect that it is unlikely to explain the main results, which are consistent with other studies.
Finally, we could be dealing with misclassifi-cation bias. Misclassification of non-hypertensives and hypertensives could lead to underestimation of any difference between the two groups, biasing the data towards the null. Differential reporting of other risk factors (i.e., information bias), could lead to overestimation or underestimation of the odds ratios. We do not believe that misclassification bias and differential reporting are likely, as a check of level and medication use showed that the two groups were properly classified.
Although AAs are at high risk of stroke, there may be AAs who are at lower risk of recurrent stroke and poor outcome after recurrent stroke. These hypotheses can be tested in the AAASPS. We speculate that African American patients in AAASPS who do not have a medical history of htn, diabetes mellitus or hyperglycemia, cardiac disease, or prior stroke may be less likely to have recurrent stroke or more likely to have better outcome if stroke does recur. Based on the Perindopril Protection Against Recurrent Stroke Study (PROGRESS) and observational data, however, we now know that the relationship between htn and stroke is a continuum whereby even patients with high normal or normal blood pressures are at risk of stroke, and lowering of blood pressure among non-hypertensives may reduce the risk of recurrent stroke.